Unseen

From Author Wars - https://authorwars.com/publications/unseen-417171.html

Overview:

Title: Unseen
Author: uncredited
Year: 2013
ISBN-10: 9781444915853
Publisher: Hodder Children's Books
Price: £6.99
Pages: 304
Binding: Trade Paperback
Type: Novel
Title Reference: Unseen
Notes: "Created by L. J. Smith" on the cover. Unlike the almost-simultaneous US edition, it doesn't list the name of the writer. Data from Amazon UK as of 2013-05-12.